The ability to identify protein post-translational modifications (PTMs) in complex biological samples is increasingly important in modern biomedical research. This proposal requests funds for the purchase of a ThermoFisher LTQ Orbitrap XL Mass Spectrometer equipped with nanoflow liquid chromatography and electron transfer dissociation (ETD) system. This will be the center piece for the proteomics platform for challenging PTM analyses. This instrument will provide ultra high resolution and high mass accuracy for confident protein identification and have unique features for multi-stage tandem mass spectrometry and novel dissociation methods for PTM analysis. There are no similar instruments to serve the NIH user group of 10 major and 7 minor users within a 60-mile radius of the Purdue University West Lafayette campus. The addition of the LTQ-Orbitrap mass spectrometer on the Purdue campus will have significant impact on the capacity of the biomedical research community to conduct leading edge basic and applied research. This effort will complement investigator-based research on instrument development and applications and provide a platform for timely transfer of state-of-art approaches in PTM mapping to a broader group of biologists. The home academic units, the Purdue Cancer Center and the Bindley Bioscience Center, will work cooperatively with the PIs to ensure the proper management and optimum conditions for high quality data production. The instrument will provide a vital component of the PTM analysis platform and serve as a major analysis tool for several members of the Purdue Cancer Center.